Data converter circuits, such as analog-to-digital converters (ADCs) can include circuits for processing a digital signal once it has been sampled. For example, in sigma-delta type ADCs, a sigma-delta modulator can generate a modulated bit stream which can then be sampled and digitally filtered. Conventionally, many IC devices include circuits designed for a particular type of filtering. For example, some conventional ADCs can include a sigma-delta modulator followed by a decimation (or sinc) filter circuit designed for a particular response. In particular, a decimation filter can be designed for a frequency response based on the noise shaping presented by the sigma-delta modulator. A limitation to conventional digital filter approaches can be limited flexibility. A digital filter can be designed for a particular application. Accordingly, to accommodate other applications can require additional value integrated circuit (IC) device area.
Digital filter functions can also be realized by code executed by a processor (e.g., firmware of a system). However, firmware based digital filtering can be slower in performance than a digital filter circuit, and can tie up processor resources and consume processor power. Further, accommodating different filter types may require additional code, or delays as new code is loaded between the implementation of different filter types.